Luminous electrical discharge tube



June 17, 1930'. .J. J. MAD-NE Y 15164,(148` Luminous ELEGTRIICAL'DISCHARGE TUB Filed V13%'.51'7.,Y 1927 Patented .lune 17, 1930 UNITED STATES PATENT] oFFlcE JOHN J. MADINE, OF CLEVELAND, OHIO, ASSIGNOR TO 'UNl RAY GAS CORPORATION,

OF CLEVELAND, OHIO, A CORPORATION F NEVADA.

LUMINOUS ELECTRICAL DISCHARGE TUBE Application led December 17, 1927. Serial No. 240,903.

This invention relates to luminescent electrical discharge tubes and more particularly to tubes employing an inert gas such as neon and argon as the current conducting medium g and in which a small quantity of liquid such as mercury is enclosed in the tube to supply its vapor to the gaseous medium for the purpose of imparting a desired color to the light `,emanating. from the tube. In signsfmade of luminescent tubes of the character above referred to in which a .small quantity of mercury or other substance such as an amalgam, sodium or potassium, is lemployed for imparting color to the light, I'the said substance is apt to become displaced .from the endof the tube in setting up a sign, with the result that the tube when in operation has the substance .so placed`l there- .in that it is subjected to very little of the 2D ,heat generated by the passage of electric current through the tube, and consequently at times when the atmospheric temperature is low sufficient vapor is not given off to materially affect the color of the light.

The present invention has for its object to provide a tube in which the liquid or substance is trapped in the end `of the tube in contact with or adjacent an electrode so that it cannot flow into the body of the tube when the sign is tipped in the handling thereof.

A further object is to provide a liquid trap which will permit the vapor to pass readily from the trap into the body of the tube and which Will permit any liquid in the body of the tube to readily flow into the ltrap at the end of the tube.

With the above and other objects in view, the invention may be said to comprise the ,discharge tube as illustrated in the accomf panying drawings hereinafter described andI particularly set forth in the appended claims, together with such variations and modifications thereof as will be apparent to one skilled in the art to which the invention u appertains.

Referring to the accompanying drawings forming a part of this specification, 60 Figure 1 is a fragmentary view of the tube, partly in longitudinal section and partly in side elevation.l

'Fig 2 is a section taken on line 2 2 of l Fig. l.

Referring to the accompanying drawings,

the discharge tube consists 'of a body portion 1 formed ofglass -tubing which may be bent 'to any desired configuration to form a suitable sign or part of a sign, the ends of the glass tubing being closed by thimble shaped Ymetal electrodes 2 in the open lends of Which the ends of the glass tubing are sealed. The end of the glass tubing adjacent the electrode is provided with a partition member 3 integrally united with the body of the tubing and provided with a tubular central projection 44Which'extends towards the-bottom o f the electrode and forms a central passage or opening 5 establishing communication between the interior of the electrode and the body ofthe tube. The tubular projection 4 forms with the main tubefan annular space 6 which, when the tube is tipped to an angle which would cause the liquid to flow toward the body l jof the tube, will receive the liquid such as the mercury7 shown in Fig. 1 and prevent the liquid from escaping from the electrode.v The partition member thus forms a liquid retaining chamber at the end of the tube which serves as a trap preventing the escape of liquid from. the electrode, the central passage 5 permitting the vapor of the mercuryor other liquid to pass freely into the body of the tube and to mingle with the gaseous current conducting medium which ills the tube.

In the operation of the tube, during cold weather, there may be condensation of mercury in the glass body portion 1but any mercury accumulating in the body `portion of the'tube may be returned to the electrode. Y

by simply tipping the tube to an angle such that the mercury will lovv to the partition 3 and through the passage 5 into the mer cury chamber.

By maintainingthe mercury in contact with the electrode with a relatively large area of contact between the electrode and the body of mercury, heat generated in the-electrode by the passage of the electrical current is transmitted directly to the mercur so that vaporization 'of the mercury s i cient to maintain the characteristic mercury vapor only throughout the tube is insuredf Furthermore, it is to be understood that the particular form of apparatus' shown and described, and the particular procedure set forth,` are presented for purposes of explanation and illustration and that various modi-V ications ofsaid apparatus and procedure can` be made without'departing from' my invention as'denedin the appended claims.

1.`A luminescent electric discharge tube comprising a body of glass tubing having a thimble shaped electrode sealed to an end thereof, the end of said glass tubing being v formed to provide va .trap for retaining mercury within the electrode in contact j therewith, and having an opening for the passage of mercury vapor to the linterior of the glass tubing. i

2. A luminescent electric discharge.. tube :comprising abody of glass tubing' having a thimble shaped electrode sealed to an end thereof and adapted to serve as a container for mercury, the end of said glass tubing having a partition forming a chamber for retaining mercury in the electrode, said partition having a central-tubular extension projecting into the chamber and providing an annularl mercury retaining recess and a central passage permitting ow of mercury vapor from the chamber or mercury into the tube. A

3. A luminescent electric discharge tube comprisinga glass tube, an electrode closing an end of the glass-tube and having mercury supported in' contact with the interior surface thereofya partition member adjacent the electrod'eand formed integral with the glass tube,v said lpartition member co-operating with the electrode to forma mercury retaining chamber, said partition member having a tubular portion extending into the chamber andspaced from thetubular -Wall -thereof, rsaid tubular portion forming an outlet passage lfor mercury vapor.

In testimony whereof I 'aiiix my signature.

' JOHN J. MADIN 

